Since Heart Gold & Soul Silver has been announced, the Chatroom (http://www.serebii.net/chat.shtml) & WiFi Chatroom (http://www.serebii.net/chat-wifi.shtml) have been booming with discussion & trade respectively so be sure to visit them.
Welcome to Day Seven of our coverage of the games Pokémon Heart Gold & Soul Silver. This update will be ammended many times over the day so be sure to check back. As the coverage is winding down, it is probable that not much will be added but there is still a variety of things to write pages about. Be sure to check yesterday, Sunday's Saturday's, Friday's Thursday's and Wednesday's Updates for stuff as well.
Last Update - 11:25 BST
Edit @ 11:05; Swarms discovered and page added. Version Exclusives Page edited with these details
Edit @ 11:25; Still discovering more swarms and adding them

http://www.serebii.net/heartgoldsoulsilver/swarms.png (http://www.serebii.net/heartgoldsoulsilver/swarms.shtml)
In The Games Department

HeartGold & Soul Silver - Swarm Pokémon

Like previous games, HeartGold & SoulSilver contain Swarm Pokémon. These Pokémon mostly do not exist in the routes in which they swarm, however the do sometimes already exist and gain an encounter rate boost. We're still looking for locations so please bare with us. Click the picture to go to the page

http://www.serebii.net/heartgoldsoulsilver/ltsurgetrade.png (http://www.serebii.net/heartgoldsoulsilver/trade.shtml)
In The Games Department

HeartGold & Soul Silver - In-Game Trades

Like with the previous games, there are a variety of points in the game where you can trade your Pokémon with a variety of in-game characters. I have compiled a list detailling all of these in-game trades as well as the details for each of the Pokéon. Click the picture to go to the page